Humic acids removal in a photocatalytic membrane reactor with a ceramic UF membrane

The investigations on the influence of TiO2 photocatalyst (Aeroxide (R) P25) loading, feed cross-flow velocity (CFV) and feed water composition on the fouling of ceramic TiO2 ultrafiltration membrane and removal of humic acids (HA) in a photocatalytic membrane reactor (PMR) are presented. Moreover, the stability of the ceramic membrane after 400 h of operation in the PMR is discussed. In case of model solution of HA in ultrapure water it was revealed that by an increase of TiO2 loading from 0.5 to 1.5 g/dm(3) the membrane fouling can be avoided. Alkaline conditions (pH 9) had a negative influence on the permeate flux and humic acids removal, whereas at pH 3 and pH 6.5 no membrane fouling was noticed. In the presence of HCO3-, SO42- and HPO42- at both low and high concentrations the membrane fouling was more severe than in the absence of these species, what was attributed to a lower efficiency of HA removal in the feed. Addition of Ca2+ and Mg2+ to the feed containing the inorganic anions allowed to improve the efficiency of HA removal and reduce membrane fouling. After 400 h of PMR operation a deterioration of membrane separation properties was observed what was attributed to the abrasive action of photocatalyst particles. (C) 2015 Elsevier B.V. All rights reserved.